Ball Grid Arrays (BGA) are widely used to electrically and mechanically connect substrates (typically ceramic) carrying semiconductor chips to a card. The BGA commonly consists of an array of metal balls which are soldered to connecting pads on both the card and the substrate.
Typically, the card (which usually consists of an FR4 body material with internal copper wiring) will have a much greater coefficient of thermal expansion than will the ceramic substrate that it is attached to. Consequently, during operation, as the entire assembly becomes heated, there is a strain imposed upon the BGA connections due to these differential expansions of the card and substrate. With repeated on-off operating cycles, the BGA connections eventually fatigue and fail by creating an open circuit or a circuit of high resistance.
U.S. Pat. No. 5,535,526 (White), assigned to International Business Machines Corporation, Armonk, New York, the disclosure of which is incorporated herein by reference, teaches a chip connected to an organic chip carrier substrate via solder, and wherein the organic chip carrier substrate is connected to a circuit board via connect balls.
U.S. Pat. No. 5,691,041 (Frankeny), assigned to International Business Machines Corporation, Armonk, N.Y., the disclosure of which is incorporated herein by reference, teaches a chip connected to a printed circuit board via an interposer.
Therefore, there is a need in the art to have an interconnect package where a substrate secured to at least one chip, has at least one organic interposer secured to the substrate with at least one first interconnect material or a set of first interconnect materials and at least one organic board secured to an organic interposer using at least one second interconnect material or a set of second interconnect materials, wherein the first interconnect material or the set of first interconnect materials has an onset of melting that is substantially above the onset of melting of the second interconnect material or second set of materials. This is of course neither taught nor disclosed by the prior art.